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At least 19 recordsLinked to original sources
PubMed1997

Volume of luteal tissue and concentration of serum progesterone in cows bearing homogeneous corpus luteum or corpus luteum with cavity.

Ultrasonographical examinations of ovarian structures were performed in 27 inseminated cows at estrus days and on days 4, 9, 20, 25, 30, and 40 after ovulation. Three cows were used twice. Corpora lutea (CLs) with a cavity were compared with homogeneous CLs. in pregnant and nonpregnant cows. Diameters and volumes of CLs and cavities, as well as volumes of luteal tissue and concentrations of serum progesterone were determined. The volumes of the structures were calculated using a mathematical formula for a rotary ellipsoid. Homogeneous CLs and CLs with a cavity and their luteal tissue reached a maximum volume in nonpregnant and pregnant cows on day 9 after ovulation. At this time, CLs volumes were 7.52 +/- 3.14 (homogeneous CLs, n = 4) and 4.54 cm3 (CLs with a cavity, n = 1) in nonpregnant cows, and 6.05 +/- 1.71 (homogeneous CLs, n = 10) and 9.54 +/- 2.67 cm3 (CLs with a cavity, n = 15) in pregnant cows. The volumes of luteal tissue were 7.52 +/- 3.14 and 4.33 cm in nonpregnant cows and 6.05 +/- 1.71 and 8.62 +/- 3.46 cm3 in pregnant cows. Concentrations of progesterone in peripheral blood in pregnant cows bearing a homogeneous CLs or CLs with a cavity on day 9 were 3.15 +/- 0.69 ng ml-1 and 4.12 +/- 1.28 ng ml-1, respectively. The concentrations of progesterone were higher in pregnant cows in comparison with nonpregnant cows. CLs with a cavity in pregnant cows contained a higher volume of luteal tissue and higher secretory activity compared to homogeneous.

Animals↗
PubMed1997

Localization of steroidogenesis and steroid receptors in human corpus luteum. Classification of human corpus luteum (CL) into estrogen-producing degenerating CL, and nonsteroid-producing degenerating CL.

In the analysis of the regulation of human corpus luteum, it is very important to localize the sites of specific steroid hormone production to obtain a better understanding of luteal function. We have examined expression of steroidogenic enzymes, steroid receptors, and adrenal 4 binding protein (Ad4BP), a transcription factor of steroidogenesis, in corpus luteum of normal cycling human ovary. Corpus luteum can be classified into four different stages from ovulation to complete regression or fibrosis based on these findings: (1) corpus luteum, (2) steroid-producing degenerating corpus luteum or SPDCL, (3) nonsteroid producing or NSPDCL, and (4) corpus albicans. Corpus luteum in the luteal phase is characterized as follows: (a) the expression of P450scc (cholesterol side chain cleavage), 3 beta HSD (hydroxysteroid dehydrogenase), and Ad4BP in almost all the luteinized granulosa and theca cells, consistent with active progesterone biosynthesis; (b) expression of estrogen-producing P450arom (aromatase) in luteinized granulosa cells, indicating active estrogen production and that of P450c17 (17 alpha hydroxylase) in luteinized theca cells, and (c) expression of progesterone receptor (PR) and androgen receptor (AR) in both luteinized granulosa and theca cells. SPDCL correspond to corpus luteum undergoing regression or degeneration in the following cycle and are characterized as follows: (a) absence of all the steroidogenic enzymes and Ad4BP in the luteinized granulosa cells, suggestive of hormonally inactive nature of these cells and (b) marked expression of P450scc, 3 beta HSD, P450c17 and Ad4BP in luteinized theca cells. NSPDCL is characterized as the absence of all the steroidogenic enzymes and sporadic expression of Ad4BP in luteinized theca cells. These findings indicate that luteal cells remain even after losing expression of steroidogenic enzymes, consistent with a prolonged process of degeneration or regression of human corpus luteum. In corpus albicans, all the cells were replaced by fibrosis and steroidogenic enzymes; steroid receptors and Ad4BP were not expressed at all. Localization of steroidogenesis in human corpus luteum has thus provided new insights into understanding of its biological features.

Corpus Luteum↗
PubMed1996

Differences of microvascular endothelium in the bovine corpus luteum of pregnancy and the corpus luteum of the estrous cycle.

The purpose of the present study was to investigate potential modulations of endothelial cells of the bovine corpus luteum (CL) during pregnancy. Luteal endothelia of pregnant and non-pregnant cows were isolated and purity of cultures was verified by flow cytometric quantification of three independent endothelial markers (von Willebrand factor, angiotensin converting enzyme, Bandeiraea simplicifolia agglutinin I ligands). Different cellular parameters including light and electron microscopical investigation of morphology and growth characteristics as well as quantification of cellular lectin binding sites were compared. Extensive heterogeneity between luteal endothelial cells in pregnant and non-pregnant animals could be demonstrated, reflected in functional attributes like angiogenic activity, ultrastructural characteristics and the quantitative expression of cellular carbohydrates. Two different morphological types of cells ("cob-blestone growth pattern' and "arcuate growth pattern') were isolated from the CL of pregnancy as well as from the cyclic CL. Spontaneous angiogenic activities, including cellular migration in band-like structures and formation of ring-like structures, were observed in endothelial cells isolated from the CL of pregnant cows exclusively. This strongly suggests that microvascular luteal endothelium of pregnant animals, in contrast to the one of non-pregnant animals, is able to produce quantitatively and/or qualitatively specific angiogenesis factor(s). Heterogeneity between luteal endothelial cells in the pregnant and non-pregnant animal could also be demonstrated by quantification of lectin (Bandeiraea simplicifolia agglutinin I, concanavalin A, Dolichos biflorus agglutinin, Ulex europaeus agglutinin I, wheat germ agglutinin) binding sites: quantitative expression of specific endothelial cell surface carbohydrates could be correlated to the status of pregnancy, thus emphasizing the actual need of quantification of lectin binding.

Animals↗
PubMed2005

Angiogenesis in the human corpus luteum: changes in expression of angiopoietins in the corpus luteum throughout the menstrual cycle and in early pregnancy.

CONTEXT: Blood vessel stabilization is regulated by angiopoietins and important for angiogenesis in the corpus luteum. OBJECTIVE: To study angiogenesis and blood vessel stabilization in the human corpus luteum, changes in expression of angiopoietin (Ang)-1, Ang-2, and their specific receptor, Tie-2, together with the number of blood vessels and pericytes were examined in the corpus luteum throughout the menstrual cycle and in early pregnancy. DESIGN: The number of blood vessels and pericytes was determined by immunohistochemistry for CD34 and alpha-smooth muscle actin, respectively. Ang and Tie-2 expression were examined by immunohistochemistry or RT-PCR. RESULTS: The number of blood vessels increased during the early luteal phase, whereas the number of pericytes was small in the early luteal phase and increased in the midluteal phase, suggesting that angiogenesis is undergoing during the early luteal phase and blood vessels are stabilized in the midluteal phase. Blood vessels and pericytes decreased in number during the late luteal phase. The increased number of both blood vessels and pericytes seen in the corpus luteum of early pregnancy suggests that angiogenesis is undergoing accompanied by blood vessel stabilization. Ang-2 expression with low Ang-1 expression was found during the early luteal phase. Thereafter, increasing Ang-1 expression during the midluteal phase, declining Ang-1 expression with continued Ang-2 expression during the late luteal phase, and relatively high Ang-1 expression in early pregnancy were observed. CONCLUSIONS: The change in Ang expression is closely associated with angiogenesis, blood vessel stabilization, and blood vessel regression during the divergent phases of luteal formation, luteal regression, and luteal rescue by pregnancy.

Actins↗
PubMed2002

Development and regression of non-capillary vessels in the bovine corpus luteum.

The corpus luteum life cycle is accompanied by capillary growth, maturation and degeneration. Arterial blood vessels are thought to undergo hyperplasia and hypertrophy during the stage of regression, as is the case with non-capillary vessels. In this study, we used morphological studies to show that the development of non-capillary vessels occurs at other corpus luteum stages. Non-capillary vessels were present at the developmental stage of the corpus luteum, and increased markedly in number in the subsequent stages. After double-staining for ASM-1 actin and Ki-67 nuclear antigen, the proliferation of smooth muscle cells (SMCs) was only detected during stages of development and secretion. When the capillaries had disappeared at the regression stage, the arterial blood-vessel walls thickened noticeably. This was attributed to the development of fibroelastosis as shown by staining for collagenous and elastic fibres. In conclusion, the bovine corpus luteum represents a physiological model for studying arteriolization at all stages of development and secretion. At the regression stage, arterioregression sets in.

Animals↗
PubMed1992

Conservative treatment of ectopic pregnancy and its effect on corpus luteum activity.

Corpus luteum activity was monitored in 15 women undergoing nonsurgical management of ectopic pregnancy with local methotrexate injection followed by alternating oral methotrexate and citrovorum factor (group A, n = 8) or local methotrexate injection alone (group B, n = 7). All patients initially demonstrated a viable corpus luteum (plasma progesterone ranged from 1.4 to 19 ng/ml). The treatment was successful in 14, with the exception of one whose tube ruptured 11 days after local administration of methotrexate, despite a continuous decrease in beta human chorionic gonadotropin, 17 beta-estradiol and plasma progesterone levels. There seems to be no correlation between the success of the treatment and the behavior of beta human chorionic gonadotropin, 17 beta-estradiol and plasma progesterone. Three patients from group A and two from group B displayed an initial rise in beta human chorionic gonadotropin following the initiation of the therapy, but the corpus luteum response differed. In group B patients, 17 beta-estradiol and plasma progesterone levels increased in parallel with beta human chorionic gonadotropin. Group A patients displayed a continuous decrease in 17 beta-estradiol and plasma progesterone levels despite the elevation of beta human chorionic gonadotropin, suggesting a possible effect of the systemic methotrexate on corpus luteum activity.

Adolescent↗
PubMed1974

Biosynthesis of retinal in bovine corpus luteum.

Bovine corpus luteum tissue was sliced and incubated with beta-[15,15'-(3)H]carotene. The conversion of radioactive beta-carotene into radioactive retinal was substantiated utilizing column chromatography, thin-layer chromatography, high-speed liquid chromatography, and a derivative formation. Lowering of the incubation temperature to 20 degrees C or boiling the tissue eliminated the conversion of beta-carotene to retinal. In addition, other carotenoids and possible oxidation products of beta-carotene in the corpus luteum were investigated. Our results indicate that the bovine corpus luteum possesses the ability to synthesize retinal in situ, which may play a role in reproductive functions.

Animals↗
PubMed1991

Expression, action, and steroidal regulation of insulin-like growth factor-I (IGF-I) and IGF-I receptor in the rat corpus luteum: their differential role in the two cell populations forming the corpus luteum.

The overall aim of this investigation was to examine the expression and steroidal regulation of insulin-like growth factor-I (IGF-I) and the IGF-I receptor in the rat corpus luteum and to examine the specificity of IGF-I action in the two luteal cell populations. We first examined whether the corpus luteum expresses the IGF-I and IGF-I receptor genes. Using a solution hybridization/RNase protection assay, IGF-I and IGF-I receptor mRNAs were represented by protected bands 224 and 265 bases in length, respectively. In addition, Northern blot analysis showed that, as in liver, rat IGF-I and IGF-I receptor cDNAs hybridized with 7.5-, 1.8-, and 0.8- to 1.2-kilobase transcripts and an 11-kilobase transcript, respectively. Both IGF-I and IGF-I receptor mRNAs were detected on all days of pregnancy tested (days 5-21). Since the rat corpus luteum increases remarkably in size and steroidogenic capacity at midpregnancy due to estradiol stimulation, we determined whether these developmental changes are accompanied by an increased expression of the IGF-I and/or IGF-I receptor genes. Total RNA was isolated from corpora lutea of day 12 hypophysectomized-hysterectomized rats treated with or without estradiol for 3 days. Estradiol caused a clear and marked reduction in IGF-I and IGF-I receptor mRNA. [125I]IGF-I bound with high specificity and affinity to luteal cell membranes. Large and small cell populations forming corpora lutea of day 3 and 14 pregnant rats were separated by elutriation and used for the determination of binding activity and for cell culture, respectively. IGF-I receptors were found to be localized principally in the large luteal cell population. The small luteal cells had approximately 6.5-fold less IGF-I-binding activity. The difference in binding activity in both cell populations was reflected in the ability of both cell types to respond to IGF-I. IGF-I (25 ng/ml) had a profound effect on the production of progesterone by the large luteal cells. No stimulatory effect of IGF-I on the small luteal cells was observed. Addition of estradiol (10 ng/ml) to the cell culture remarkably enhanced IGF-I stimulation of progesterone biosynthesis by the large luteal cells. In summary, the results of this investigation have revealed that the corpus luteum of the pregnant rat is a major site of expression of both the IGF-I and IGF-I receptor genes.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2000

Prostaglandin metabolism in the ovine corpus luteum: catabolism of prostaglandin F(2alpha) (PGF(2alpha)) coincides with resistance of the corpus luteum to PGF(2alpha).

To examine possible mechanisms involved in resistance of the ovine corpus luteum to the luteolytic activity of prostaglandin (PG)F(2alpha), the enzymatic activity of 15-hydroxyprostaglandin dehydrogenase (PGDH) and the quantity of mRNA encoding PGDH and cyclooxygenase (COX-2) were determined in ovine corpora lutea on Days 4 and 13 of the estrous cycle and Day 13 of pregnancy. The corpus luteum is resistant to the action of PGF(2alpha) on Days 4 of the estrous cycle and 13 of pregnancy while on Day 13 of the estrous cycle the corpus luteum is sensitive to the actions PGF(2alpha). Enzymatic activity of PGDH, measured by rate of conversion of PGF(2alpha) to PGFM, was greater in corpora lutea on Day 4 of the estrous cycle (P < 0.05) and Day 13 of pregnancy (P < 0.05) than on Day 13 of the estrous cycle. Levels of mRNA encoding PGDH were also greater in corpora lutea on Day 4 of the estrous cycle (P < 0. 01) and Day 13 of pregnancy (P < 0.01) than on Day 13 of the estrous cycle. Thus, during the early estrous cycle and early pregnancy, the corpus luteum has a greater capacity to catabolize PGF, which may play a role in the resistance of the corpus luteum to the actions of this hormone. Levels of mRNA encoding COX-2 were undetectable in corpora lutea collected on Day 13 of the estrous cycle but were 11 +/- 4 and 44 +/- 28 amol/microgram poly(A)(+) RNA in corpora lutea collected on Day 4 of the estrous cycle and Day 13 of pregnancy, respectively. These data suggest that there is a greater capacity to synthesize PGF(2alpha), early in the estrous cycle and early in pregnancy than on Day 13 of the estrous cycle. In conclusion, enzymatic activity of PGDH may play an important role in the mechanism involved in luteal resistance to the luteolytic effects of PGF(2alpha).

Animals↗
PubMed1997

Endothelial cell proliferation follows the mid-cycle luteinizing hormone surge, but not human chorionic gonadotrophin rescue, in the human corpus luteum.

The corpus luteum is essential for the maintenance of early pregnancy in women. Angiogenesis may be one factor involved in luteal rescue. The aim of this study was to determine the changes in endothelial cell proliferation throughout the luteal phase and in human chorionic gonadotrophin (HCG)-simulated early pregnancy. Human corpora lutea obtained throughout the luteal phase and in simulated early pregnancy were immunostained with antibodies for endothelial and proliferating cells. Number and distribution of endothelial and proliferating cells were examined. Endothelial cells were least abundant in the early luteal phase, increasing in the mid-luteal phase (P < 0.03). Endothelial numbers did not differ significantly between the late and the rescued corpora lutea. Endothelial cell proliferation was greatest in the early luteal phase and continued at a lower level during later stages. Simulated early pregnancy resulted in no change in endothelial cell proliferation. These results showed that a high degree of endothelial cell proliferation is associated with formation of the human corpus luteum. Unchanging levels of proliferation following HCG treatment (for 5-8 days from day 12 to day 16 post-ovulation, at 125 IU to 16,000 IU, following a daily doubling of dose) suggest that alternative processes are involved during luteal rescue.

Adult↗
PubMed1988

The corpus luteum.

Normal corpus luteum function is determined by function in the follicular as well as the luteal phase. In the follicular phase adequate follicle-stimulating hormone (FSH) and oestrogen stimulation are required for granulosa cell mitosis and luteinizing hormone (LH) receptor synthesis. An increase in LH pulse frequency may also be necessary for adequate oestrogen synthesis and preparation of follicular cells for luteinization and secretion of progesterone. The nature of LH release may also influence luteal function and pre-ovulatory progesterone may increase the responsiveness of the follicle to gonadotrophins. The thecal vascular network becomes extensive around pre-ovulatory follicles and may influence access of gonadotrophins and/or the ability of follicular cells to respond to them. Further vascularization is an early feature of luteinization. Angiogenic factors are found in luteal tissue and prostacyclin increases luteal blood flow. The corpus luteum consists of large cells which secrete most of the progesterone and have prostaglandin F2 alpha receptors and small cells which are responsive to LH. In the luteal phase subnormal luteal function has not been associated with a reduction in LH concentration, pulse frequency or amplitude. The number and occupancy of LH receptors and adenylate cyclase activity do not appear to be altered by a reduction in luteal function. Low density lipoprotein provides the substrate and somatomedin C modulates among other hormones' influences, progesterone production. In addition to the cAMP second messenger system phosphatidyl inositol metabolism may also be associated with LH stimulation. Luteolysis is an active process; prostaglandin F2 alpha or lipoxygenase products and possibly an endogenous GnRH-like ovarian hormone may mediate it as also may oxytocin in some species.

Corpus Luteum↗
PubMed1996

Characterization and expression of vascular endothelial growth factor (VEGF) in the ovine corpus luteum.

The corpus luteum undergoes tremendous growth, development and regression each oestrous or menstrual cycle. These changes are reflected by equally impressive growth and regression of the luteal vasculature. We have previously shown that angiogenic factors from corpora lutea are primarily heparin binding and that one of these factors is similar to vascular endothelial growth factor (VEGF). In an effort to identify this factor, and to define its role in luteal vascular development, the cDNA for the coding region of ovine VEGF was sequenced and a sensitive RNase protection assay was developed to quantitate mRNA encoding VEGF in luteal tissues from ewes in the early (days 2-4), mid- (day 8) and late (days 14-15) stages of the oestrous cycle. In addition, an N-terminal peptide was synthesized from the translated ovine cDNA sequence for VEGF and an antiserum was raised against this peptide for use in western immunoblotting procedures. Nested reverse transcriptase (RT)-PCR of RNA from ovine corpora lutea resulted in three products that correspond in size to the alternatively spliced variants of VEGF (VEGF120, VEGF164, and VEGF188) predicted from other species. The RNase protection assay revealed that the proportion of mRNA encoding VEGF was 2- to 3-fold greater on days 2-4 than on day 8 or days 14-15. Densitometric analysis of gels from the RNase protection assay showed that VEGF120 represented approximately one third of the total mRNA encoding VEGF in the corpus luteum and that this proportion did not vary with stage of the oestrous cycle. SDS-PAGE and western immunoblot analysis of a homogenate from corpora lutea showed a single 18 kDa protein. These data demonstrate that VEGF is expressed in luteal tissue throughout the ovine oestrous cycle and that expression of mRNA encoding VEGF is upregulated during the period of rapid luteal development, when luteal vascular growth is at its maximum.

Amino Acid Sequence↗
PubMed2003

Differential regulation of apoptosis in the corpus luteum of pregnancy and newly formed corpus luteum after parturition in rats.

Apoptosis contributes to luteal regression in many species. In the postpartum rat, there are two different types of corpora lutea (CL) in the ovary: CL of pregnancy (CLP) and newly formed CL (NCL). To investigate the regulation of apoptosis in the two different types of CL during luteal regression, apoptosis and caspase-3 activity were examined in the CL obtained on Days 7, 15, and 21 of pregnancy and Days 0, 1, 3, 5, 7, and 9 postpartum. Furthermore, the effect of lactation on apoptosis in the CL was examined in two groups of postpartum rats: lactating rats that nurse more than 10 pups, and nonlactating rats that nurse no pups. Apoptotic cells were detected after Day 21 of pregnancy. In the CLP, remarkable increases in the number of apoptotic cells on Days 5 and 9 postpartum were observed in nonlactating rats (P < 0.01), but not in lactating rats. Changes in caspase-3 activity in the CLP were not consistent with those in number of apoptotic cells. In the NCL, an increase in apoptosis was found only on Day 5 postpartum in nonlactating rats (P < 0.01), but not in lactating rats. Changes in caspase-3 activity in the NCL were consistent with those in number of apoptotic cells. In conclusion, apoptosis is, at least in part, involved in luteal regression after parturition, and lactation appears to inhibit apoptosis. This study also suggests the presence of a caspase-3-independent mechanism for apoptosis in CLP regression in the rat.

Animals↗
PubMed1978

Production a corpus luteum angiogenic factor responsible for proliferation of capillaries and neovascularization of the corpus luteum.

Factors controlling the changes in the vascular pattern of the ovary that occur during the reproductive cycle have been investigated. By using the rabbit cornea, the abilities of ovarian corpus luteum and of follicles to induce neovascularization have been compared. While the corpus luteum is capable of inducing neovascularization, the follicles do not have this ability. It is therefore likely that the corpus luteum actively participates in its own neovascularization by secreting a factor that we have called "corpus leutem angiogenic factor" (CLAF).

Angiogenesis Inducing Agents↗